Is it currently possible to have two AppConfig instances in cache.app_configs? I would assume that can't happen without raising some error during populate.

If it is true that app_label is going to be ensured to be a unique key, what are the advantages of using app-name as the lookup arg?

Pros: the calling code preserve's an explicit reference to the app as a fully qualified package name, cons: you may have people choosing to organize apps into different package groupings differently, which would break any usage of a full path as the key.